German patent application no. 10 2006 058 613.1 describes a canister vacuum cleaner having a housing containing an electric motor and a storage battery pack including a plurality of storage battery cells for energizing said electric motor, the energization being at a voltage of more than 42 volts, and a connector assembly being provided for establishing electrical contact between the storage battery pack and the electric motor.
Conventional storage battery-powered electrical appliances are generally rated for an operating voltage of less than 42 volts. This value corresponds to the threshold specified in VDE 0700 for safety extra-low voltage. There are applications where such an operating voltage is not sufficient to deliver the desired power, especially when the current load is limited. Examples of this include the vacuum cleaners described in the above-referenced patent application, which are intended to provide a satisfactory suction power both during mains operation and battery operation. Therefore, a number of storage battery cells are used, which altogether generate an operating voltage of more than 42 volts, this voltage preferably being around 100 volts.
Since contact of persons with such a voltage must be prevented both during manufacture and during handling of the appliance, these persons cannot be expected to handle the appliance in the same way as devices containing extra-low voltage loads (flashlights, remote controls, etc.). In such devices, the storage battery cells required are individually inserted into a receiving compartment of the device, and then electrically interconnected via bridges provided therein. Using such a procedure, the voltage with which the user may come in contact would increase with every cell inserted. Storage battery packs, which are composed of a plurality of previously interconnected cells in a rigid inaccessible battery housing, also do not provide any solution to this problem because the connectors needed for establishing electrical contact between the storage battery pack and the electric motor would still be a potential hazard.